This is interesting, I have Python 2.7.3 installed and I get the same error when trying to add the mintMenu to the top panel. I'm not having any issues with it on the default bottom location, and the other two menus can be added just fine. Using Mint 13 with Mate and all official updates installed.

@pleabargain: We can call this fixed, as mintMenu is written for Python 2.7 and you had set Python 3 as the default. As shared on your other topic, that will break various system tools. This includes the mintMenu.

@David Rahrer: You can only run one instance of the mintMenu. If you want to have it in your top panel, first delete it in your bottom panel (I've confirmed this works, and also confirmed that then trying to add it to the bottom panel will give the same error). There can be only one

In various places on the web other users have plaintively asked what to do when Mint's main Menu/cogwheel button disappears from the bottom left corner due to one mischance or another. I don't know about MATE, but in my 32-bit Cinnamon, right-clicking on an empty spot on the bottom panel does nothing at all. To restore the missing Menu button/cogwheel it is necessary to right-click on any other icon there (eg: "Show Desktop"), then left-click on "Add/remove applets" in the pop-up box which next brings up the settings box labelled "Cinnamon Settings - Applets". It has a button labelled "Restore to default", and left-clicking that restored the Menu button/cogged wheel to it's original spot at the far left of the bottom panel.

I eventually found I could add a menu to the bottom bar ("panel") - this isn't quite as convenient as the cogwheel, but I think, between the "main menu" and the "Mint menu", it shows all the same options. Notably, I can get to the Synaptic package manager again, and also the "Software Manager" (MintInstall 7.3.9). I tried reinstalling Python (2.7.3-Oubuntu2) from the synaptic package manager. it claimed success but awfully quickly, and noticed this within the Details:"Waited for dpkg -assert-multi-arch but it wasn't there - dpkg Go (10: no child process)"

(When I select software in the Software Manager, it just freezes up and never does anything.)

I tried launching the Mate control center from the command line. I can see STDERR that way. "No module name pygtk" comes up when I click on Desktop Settings (which otherwise does nothing).

To sum up: I've got a working Python 2.7.3 installation; it's the default Python version, but some parts of MATE (cogwheel, update manager, desktop settings applet) are still not happy. Perhaps I need specific modules not included in the standard Python install.

If the package manager's not working, is there a quick way to reinstall the exact version/configuration/module set of Python 2.7 that I had before?

I could actually add it back on. I also got the error once when i first tried to add 'mintMenu' from the 'add to panel' menu. so instead i added the 'Main Menu' . Later when i tried to add the 'mintMenu' again, it allowed me. To move it back to the corner just uncheck the 'lock to panel' of the panel showing the windows(right click on the the three horizontal lines at the corner). After that you can place your advance menu (or any panel item) at the corner. hope this helped.